Apparatus for obtaining zinc by electrolysis.



No. 70I,2l6. I Patented May 27, I902.

L. MDND.

APPARATUS FOR OBTAINING ZINC BY ELECTROLYSIS.

(Application filed Mar. 4, 1902.) (No Model.) 3 Sheets-Sheet I.

715%mnm). 1720022222? Jfwz Patented May 27, I902.

I L. MUND.

APPARATUS FOR OBTAINING ZINC BY ELECTROLYSIS.

(Application filed Mar. 4, 1902.)

3 Sheefi-Sheet 2.

(No Model.)

m: NORRIS PETERS cu, PNOTO-LITHOH wasumcrom b. c.

N0. 70l,2l6. Patented May 27, I902.

- L. mono. APPARATUS FOR OBTAINING ZINC BY ELECTRULYSIS.

(Application filed Mar. 4, 1902.) (No Model.) 3 Sheets-Sheet 3.

m: NORRIS wzrcas co. moro-u'mo. msnmcrou. o. c:

UNITE STATES PATENT OFFICE.

LUDWIG MONI), OF LONDON, ENGLAND.

APPARATUS FOR OBTAINING ZINC BY ELECTROLYSIS.

SPECIFICATION forming part of Letters Patent No. 701,216, dated May 27, 1902.

Application filed March 4, 1902- To all whom it may concern:

Be it known that I, LUDWIG MOND, a citizen of England, residing at 20 Avenue road, Regents Park,London, England, have invented certain new and useful Improvements in Apparatus for Obtaining Zinc by Electrolysis, (for which I have applied for a patent in Great Britain, dated March 19, 1901, No. 5,764; in Spain, dated December 24, 1901; in Germany, dated August 8, 1901, and November 27, 1901; in France, dated December 13, 1901; in Belgium, dated December 14, 1901; in Italy,dated December 18, 1901; and obtained a patent in Canada,dated November12, 1901, No.73,705,) of which the following is a specification.

For depositing zinc from its solutions, and more particularly from alkaline solutions, by electrolysis a great difficulty has been found in obtaining the metal in a coherent form. It is usually obtained in the form of a spongy mass, which oxidizes so readily on being withdrawn from the electrolytic bath that on at tempting to melt it only a small percentage of the zinc originally deposited is obtained as metal, the bulk presenting itself as oxid. Various means have been proposed to overcome this difficulty, such as depositing the zinc upon revolving cathodes in the form of disks or cylinders which are partly immersed in the electrolyte. WVith great precautions a coherent metallic deposit of zinc can be obtained in this way up to a certain thickness, rarely exceeding, however, one-eighth of an inch, after which the deposit becomes spongy. According to my present invention, which was originally included in my application filed August 12, 1901, Serial No. 71,775, I entirely overcome this difficulty and obtain coherent metallic deposits of any thickness by employing apparatus by which the metal is subjected to a constant rubbing action under pressure While it is being deposited. For this purpose I make the cathodes upon which the zinc is to be deposited cylinders of conducting material and arrange several of them in a row, each touching the next, in one electrolytic bath. These cylinders are provided with shafts moving in bearings which are mounted so that they can slide, and I apply pressure upon all or several of these cylinders by means of weights, springs, levers, or other mechanical device, which presses the Serial No. 96.691. (No model.)

modified ways for carrying out my invention,

as I will describe with reference to the accompanying drawings.

Figure 1 is a part-longitudinal section of an arrangement of the apparatus with the cathode-cylinders arranged in a horizontal row. Fig. 2 is a part plan. Figs. 3 and 4: are

respectively an enlarged cross-section and a front view of one of the bearings of the shaft of cylinder at. Fig. 5 is a longitudinal section of an arrangement in which the cathodecylinders are superposed, Fig. 6 being a section on the line 8 8 of Fig. 5 and Fig. 7 a sectional plan and Fig. 8 an enlarged detail of this construction.

Referring to Figs. 1 and 2, the cylinders a and b b have their shafts mounted in bearings c and d d, pressed against each other by springs e or their equivalents. All the cylinders may be rotated by any convenient motor; but I prefer to drive only one of them, I), as bya belt fon pulley g, as shown, the others, a b, being rotated by frictional contact. I make these cylinders of slightly-difierent diameters, a smaller between each two larger, so that the same points on their circumferences do not come in contact until after many revolutions. I also give alternate cylinders 66 besides rotation a to-and-fro longitudinal motion forproducing the abovedescribed rubbing action and also to avoid the formation of grooves in the deposited metal. This to-and-fro motion, which need not exceed an inch, may be obtained, as shown, by cutting an inclined groove in one of the bearings and mounting on the shaft, which works in it, a roller is, fitting loosely in this groove. The bearings of the cylinder-shafts are insulated and connected to the negative terminal of a source of electricity,.or,- as shown inF-ig. 2, each of the cylinder-shafts has on its end a metallic disk Z, dipping into mercury in an insulated cup an, all of which cups are connected to the negative pole of the source of as shown in Fig. 6, so as to have all their electricity. The other pole is connected to the amalgam p, which occupies-the lower part of the cell. This amalgam is obtained in the known manner by the electrolysis of sodium or potassium chlorid with a mercury cathode, and when it is employed as anode it should be kept constantly flowing over the bottom of the cell. When such amalgam is not available, anodes may be employed of carbon or of platinum, iron, or other metals that are not oxidized by electrolytic oxygen in alkaline solution. In order to facilitate the removal of the deposited zinc, the cylinders should be coated with a little graphite or paraffin or any other suitable substance which prevents contact of the deposited zinc with the metal of the cylinder.

In the modification shown in Figs. 5, 6, and 7 the cylindrical cathodes a Z) Z) are superposed. In this case the cylinders are pressed against each other by weights 0' r, which are mounted on the shaft of the top roller 1) and are of suflicient weight to counteract the buoyancy of the cylinders in the electrolyte. The middle cylinder a receives a slight longitudinal to-and-fro motion and is of diameter slightly different from that of the other cylinders. The cathode-cylinders Ct 12 b may be made hollow, as shown, the cylindrical part of each being insulated from the two ends by rings 0 of insulating material, such as ebonite. The bearings c c and (Z for the axes of the cylinders are fitted to slide in vertical guides '21, the bearing 0 and the axis which works in it being arranged as described with reference to Figs. 3 and 4. p p are the anode-plates, which are preferably corrugated,

parts approximately equidistant from the surfaces of the cylinders. The cylinders 01, b b are connected to the circuit by a contactspring brush 'm, applied to the top roller. The cathode-cylinders being hollow, a suitable packing has to be provided to prevent the electrolyte from penetrating into them at the center. This may conveniently be effected as shown at Fig. 8, where acaoutchouc or ebonite ring 3 is compressed in the recess of the boss, so as to form-a water-tight joint by means of a steel washer t and sore w-nut u.

Having thus described the nature of this invention and the best means I know of cari rying the same into practical effect, I claim- 1. In apparatus for obtaining zinc by electrolysis, the combination of a number of cylindrical cathodes rotating in contact with each other within an electrolytic bath, means for pressing the cylinders against each other and means for producing a longitudinal rubbing action between the cylinders, substantially as described.

2. In apparatus for obtaining zinc by electrolysis, the combination of a number of c'ylindrical cathodes rotating in contact with each other within an electrolytic bath every alternate cylinder being of diameter different from that of the others, means for pressing the cylinders against each other and means for producing a longitudinal rubbing action between the cylinders, substantially as described.

' 3. In apparatus for obtaining zinc by electrolysis, the combination of a number of cylindrical cathodes rotating in contact with each other within an electrolytic bath, means for pressing the cylinders against each other, means for driving the one cylinder by external power which cylinder gives rotation to the others by frictional contact, and means for producing a longitudinal rubbing action between the cylinders, substantially as described.

4. In apparatus for obtaining zinc by electrolysis, the combination of a number of cylindrical cathodes rotating in contact with each other within an electrolytic bath, means for pressing the cylinders against each other and means for imparting a longitudinal toaud-fro motion to some or all of the cylinders for producing a rubbingaction between them, substantially as described.

5. In apparatus for obtaining zinc by electrolysis, the combination in an electrolytic bath of a number of rotating horizontal cylindrical cathodes each differing somewhat in diameter from that or those next to it, pressed toward each other by means which allow their axes to move farther apart, all these axes being mounted in sliding bearings, and one of the axes of each alternate cathode being provided with a stud engaged in an inclined groove in its bearing, so that as such cathode revolves, itis moved to and fro longitudinally, substantially as and for the purpose set forth.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

LUDWIG MOND.

Witnesses:

ALBERTO CERASOLI, A. H. BARTLETT. 

